(PHP 4, PHP 5, PHP 7, PHP 8)
var_dump — 打印变量的相关信息
此函数显示关于一个或多个表达式的结构信息，包括表达式的类型与值。数组和对象将递归展开值，通过缩进显示其结构。
对象的所有公共、私有和受保护的属性都会在输出中返回，除非该对象实现了 __debugInfo() 方法。
value要打印的表达式。
values更多要打印的表达式。
没有返回值。
示例 #1 var_dump() 例子
<?php
$a = array(1, 2, array("a", "b", "c"));
var_dump($a);
?>以上示例会输出：
array(3) {
[0]=>
int(1)
[1]=>
int(2)
[2]=>
array(3) {
[0]=>
string(1) "a"
[1]=>
string(1) "b"
[2]=>
string(1) "c"
}
}
<?php
$b = 3.1;
$c = true;
var_dump($b, $c);
?>以上示例会输出：
float(3.1) bool(true)
Keep in mind if you have xdebug installed it will limit the var_dump() output of array elements and object properties to 3 levels deep.To change the default, edit your xdebug.ini file and add the folllowing line:xdebug.var_display_max_depth=nMore information here:http://www.xdebug.org/docs/displayIf you're like me and uses var_dump whenever you're debugging, you might find these two "wrapper" functions helpful.This one automatically adds the PRE tags around the var_dump output so you get nice formatted arrays.<?phpfunction var_dump_pre($mixed = null) { echo '<pre>'; var_dump($mixed); echo '</pre>'; return null;}?>This one returns the value of var_dump instead of outputting it.<?phpfunction var_dump_ret($mixed = null) { ob_start(); var_dump($mixed); $content = ob_get_contents(); ob_end_clean(); return $content;}?>Fairly simple functions, but they're infinitely helpful (I use var_dump_pre() almost exclusively now).I post a new var_dump function with colors and collapse features. It can also adapt to terminal output if you execute it from there. No need to wrap it in a pre tag to get it to work in browsers. <?phpfunction dump_debug($input, $collapse=false) { $recursive = function($data, $level=0) use (&$recursive, $collapse) { global $argv; $isTerminal = isset($argv); if (!$isTerminal && $level == 0 && !defined("DUMP_DEBUG_SCRIPT")) { define("DUMP_DEBUG_SCRIPT", true); echo '<script language="Javascript">function toggleDisplay(id) {'; echo 'var state = document.getElementById("container"+id).style.display;'; echo 'document.getElementById("container"+id).style.display = state == "inline" ? "none" : "inline";'; echo 'document.getElementById("plus"+id).style.display = state == "inline" ? "inline" : "none";'; echo '}</script>'."\n"; } $type = !is_string($data) && is_callable($data) ? "Callable" : ucfirst(gettype($data)); $type_data = null; $type_color = null; $type_length = null; switch ($type) { case "String": $type_color = "green"; $type_length = strlen($data); $type_data = "\"" . htmlentities($data) . "\""; break; case "Double": case "Float": $type = "Float"; $type_color = "#0099c5"; $type_length = strlen($data); $type_data = htmlentities($data); break; case "Integer": $type_color = "red"; $type_length = strlen($data); $type_data = htmlentities($data); break; case "Boolean": $type_color = "#92008d"; $type_length = strlen($data); $type_data = $data ? "TRUE" : "FALSE"; break; case "NULL": $type_length = 0; break; case "Array": $type_length = count($data); } if (in_array($type, array("Object", "Array"))) { $notEmpty = false; foreach($data as $key => $value) { if (!$notEmpty) { $notEmpty = true; if ($isTerminal) { echo $type . ($type_length !== null ? "(" . $type_length . ")" : "")."\n"; } else { $id = substr(md5(rand().":".$key.":".$level), 0, 8); echo "<a href=\"javascript:toggleDisplay('". $id ."');\" style=\"text-decoration:none\">"; echo "<span style='color:#666666'>" . $type . ($type_length !== null ? "(" . $type_length . ")" : "") . "</span>"; echo "</a>"; echo "<span id=\"plus". $id ."\" style=\"display: " . ($collapse ? "inline" : "none") . ";\"> ⤵</span>"; echo "<div id=\"container". $id ."\" style=\"display: " . ($collapse ? "" : "inline") . ";\">"; echo "<br />"; } for ($i=0; $i <= $level; $i++) { echo $isTerminal ? "| " : "<span style='color:black'>|</span> "; } echo $isTerminal ? "\n" : "<br />"; } for ($i=0; $i <= $level; $i++) { echo $isTerminal ? "| " : "<span style='color:black'>|</span> "; } echo $isTerminal ? "[" . $key . "] => " : "<span style='color:black'>[" . $key . "] => </span>"; call_user_func($recursive, $value, $level+1); } if ($notEmpty) { for ($i=0; $i <= $level; $i++) { echo $isTerminal ? "| " : "<span style='color:black'>|</span> "; } if (!$isTerminal) { echo "</div>"; } } else { echo $isTerminal ? $type . ($type_length !== null ? "(" . $type_length . ")" : "") . " " : "<span style='color:#666666'>" . $type . ($type_length !== null ? "(" . $type_length . ")" : "") . "</span> "; } } else { echo $isTerminal ? $type . ($type_length !== null ? "(" . $type_length . ")" : "") . " " : "<span style='color:#666666'>" . $type . ($type_length !== null ? "(" . $type_length . ")" : "") . "</span> "; if ($type_data != null) { echo $isTerminal ? $type_data : "<span style='color:" . $type_color . "'>" . $type_data . "</span>"; } } echo $isTerminal ? "\n" : "<br />"; }; call_user_func($recursive, $input);}?><?php/** * Better GI than print_r or var_dump -- but, unlike var_dump, you can only dump one variable. * Added htmlentities on the var content before echo, so you see what is really there, and not the mark-up. * * Also, now the output is encased within a div block that sets the background color, font style, and left-justifies it * so it is not at the mercy of ambient styles. * * Inspired from: PHP.net Contributions * Stolen from: [highstrike at gmail dot com] * Modified by: stlawson *AT* JoyfulEarthTech *DOT* com * * @param mixed $var -- variable to dump * @param string $var_name -- name of variable (optional) -- displayed in printout making it easier to sort out what variable is what in a complex output * @param string $indent -- used by internal recursive call (no known external value) * @param unknown_type $reference -- used by internal recursive call (no known external value) */function do_dump(&$var, $var_name = NULL, $indent = NULL, $reference = NULL){ $do_dump_indent = "<span style='color:#666666;'>|</span> "; $reference = $reference.$var_name; $keyvar = 'the_do_dump_recursion_protection_scheme'; $keyname = 'referenced_object_name'; // So this is always visible and always left justified and readable echo "<div style='text-align:left; background-color:white; font: 100% monospace; color:black;'>"; if (is_array($var) && isset($var[$keyvar])) { $real_var = &$var[$keyvar]; $real_name = &$var[$keyname]; $type = ucfirst(gettype($real_var)); echo "$indent$var_name <span style='color:#666666'>$type</span> = <span style='color:#e87800;'>&$real_name</span><br>"; } else { $var = array($keyvar => $var, $keyname => $reference); $avar = &$var[$keyvar]; $type = ucfirst(gettype($avar)); if($type == "String") $type_color = "<span style='color:green'>"; elseif($type == "Integer") $type_color = "<span style='color:red'>"; elseif($type == "Double"){ $type_color = "<span style='color:#0099c5'>"; $type = "Float"; } elseif($type == "Boolean") $type_color = "<span style='color:#92008d'>"; elseif($type == "NULL") $type_color = "<span style='color:black'>"; if(is_array($avar)) { $count = count($avar); echo "$indent" . ($var_name ? "$var_name => ":"") . "<span style='color:#666666'>$type ($count)</span><br>$indent(<br>"; $keys = array_keys($avar); foreach($keys as $name) { $value = &$avar[$name]; do_dump($value, "['$name']", $indent.$do_dump_indent, $reference); } echo "$indent)<br>"; } elseif(is_object($avar)) { echo "$indent$var_name <span style='color:#666666'>$type</span><br>$indent(<br>"; foreach($avar as $name=>$value) do_dump($value, "$name", $indent.$do_dump_indent, $reference); echo "$indent)<br>"; } elseif(is_int($avar)) echo "$indent$var_name = <span style='color:#666666'>$type(".strlen($avar).")</span> $type_color".htmlentities($avar)."</span><br>"; elseif(is_string($avar)) echo "$indent$var_name = <span style='color:#666666'>$type(".strlen($avar).")</span> $type_color\"".htmlentities($avar)."\"</span><br>"; elseif(is_float($avar)) echo "$indent$var_name = <span style='color:#666666'>$type(".strlen($avar).")</span> $type_color".htmlentities($avar)."</span><br>"; elseif(is_bool($avar)) echo "$indent$var_name = <span style='color:#666666'>$type(".strlen($avar).")</span> $type_color".($avar == 1 ? "TRUE":"FALSE")."</span><br>"; elseif(is_null($avar)) echo "$indent$var_name = <span style='color:#666666'>$type(".strlen($avar).")</span> {$type_color}NULL</span><br>"; else echo "$indent$var_name = <span style='color:#666666'>$type(".strlen($avar).")</span> ".htmlentities($avar)."<br>"; $var = $var[$keyvar]; } echo "</div>";}?>Be careful this outputs to stdout stream (1) instead of the proper stderr stream (2).Howdy!I am working on a pretty large project where I needed to dump a human readable form of whatever into the log files... and I thought var_export was too difficult to read. BigueNique at yahoo dot ca has a nice solution, although I needed to NOT modify whatever was being passed to dump.So borrowing heavily from BigueNique's (just reworked his function) and someone's idea over in the object cloning page, I came up with the following function.It makes a complete copy of whatever object you initially pass it, including all recursive definitions and outside objects references, then does the same thing as BigueNique's function. I also heavily reworked what it output, to suit my needs.<?phpfunction var_log(&$varInput, $var_name='', $reference='', $method = '=', $sub = false) { static $output ; static $depth ; if ( $sub == false ) { $output = '' ; $depth = 0 ; $reference = $var_name ; $var = serialize( $varInput ) ; $var = unserialize( $var ) ; } else { ++$depth ; $var =& $varInput ; } // constants $nl = "\n" ; $block = 'a_big_recursion_protection_block'; $c = $depth ; $indent = '' ; while( $c -- > 0 ) { $indent .= '| ' ; } // if this has been parsed before if ( is_array($var) && isset($var[$block])) { $real =& $var[ $block ] ; $name =& $var[ 'name' ] ; $type = gettype( $real ) ; $output .= $indent.$var_name.' '.$method.'& '.($type=='array'?'Array':get_class($real)).' '.$name.$nl; // havent parsed this before } else { // insert recursion blocker $var = Array( $block => $var, 'name' => $reference ); $theVar =& $var[ $block ] ; // print it out $type = gettype( $theVar ) ; switch( $type ) { case 'array' : $output .= $indent . $var_name . ' '.$method.' Array ('.$nl; $keys=array_keys($theVar); foreach($keys as $name) { $value=&$theVar[$name]; var_log($value, $name, $reference.'["'.$name.'"]', '=', true); } $output .= $indent.')'.$nl; break ; case 'object' : $output .= $indent.$var_name.' = '.get_class($theVar).' {'.$nl; foreach($theVar as $name=>$value) { var_log($value, $name, $reference.'->'.$name, '->', true); } $output .= $indent.'}'.$nl; break ; case 'string' : $output .= $indent . $var_name . ' '.$method.' "'.$theVar.'"'.$nl; break ; default : $output .= $indent . $var_name . ' '.$method.' ('.$type.') '.$theVar.$nl; break ; } // $var=$var[$block]; } -- $depth ; if( $sub == false ) return $output ; }// var_log( $var, '$name' ) ;?>Hope it works well for you!As Bryan said, it is possible to capture var_dump() output to a string. But it's not quite exact if the dumped variable contains HTML code.You can use this instead:<?phpecho '<pre>'; // This is for correct handling of newlinesob_start();var_dump($var);$a=ob_get_contents();ob_end_clean();echo htmlspecialchars($a,ENT_QUOTES); // Escape every HTML special chars (especially > and < )echo '</pre>';?>If you want to save exactly the content of an array into a variable to save ir later for example, use this:
<?php $xml = var_export($xml, true); ?>
You'll have in your same variable the content readable, instead of written down or anything elsemade 2 nifty functions based of what some people contributed here. Hope you find them usefullusage ... call for the dump function. EG: dump($array, "Array dump");<?php////////////////////////////////////////////////////////// Function: dump// Inspired from: PHP.net Contributions// Description: Helps with php debuggingfunction dump(&$var, $info = FALSE){ $scope = false; $prefix = 'unique'; $suffix = 'value'; if($scope) $vals = $scope; else $vals = $GLOBALS; $old = $var; $var = $new = $prefix.rand().$suffix; $vname = FALSE; foreach($vals as $key => $val) if($val === $new) $vname = $key; $var = $old; echo "<pre style='margin: 0px 0px 10px 0px; display: block; background: white; color: black; font-family: Verdana; border: 1px solid #cccccc; padding: 5px; font-size: 10px; line-height: 13px;'>"; if($info != FALSE) echo "<b style='color: red;'>$info:</b><br>"; do_dump($var, '$'.$vname); echo "</pre>";}////////////////////////////////////////////////////////// Function: do_dump// Inspired from: PHP.net Contributions// Description: Better GI than print_r or var_dumpfunction do_dump(&$var, $var_name = NULL, $indent = NULL, $reference = NULL){ $do_dump_indent = "<span style='color:#eeeeee;'>|</span> "; $reference = $reference.$var_name; $keyvar = 'the_do_dump_recursion_protection_scheme'; $keyname = 'referenced_object_name'; if (is_array($var) && isset($var[$keyvar])) { $real_var = &$var[$keyvar]; $real_name = &$var[$keyname]; $type = ucfirst(gettype($real_var)); echo "$indent$var_name <span style='color:#a2a2a2'>$type</span> = <span style='color:#e87800;'>&$real_name</span><br>"; } else { $var = array($keyvar => $var, $keyname => $reference); $avar = &$var[$keyvar]; $type = ucfirst(gettype($avar)); if($type == "String") $type_color = "<span style='color:green'>"; elseif($type == "Integer") $type_color = "<span style='color:red'>"; elseif($type == "Double"){ $type_color = "<span style='color:#0099c5'>"; $type = "Float"; } elseif($type == "Boolean") $type_color = "<span style='color:#92008d'>"; elseif($type == "NULL") $type_color = "<span style='color:black'>"; if(is_array($avar)) { $count = count($avar); echo "$indent" . ($var_name ? "$var_name => ":"") . "<span style='color:#a2a2a2'>$type ($count)</span><br>$indent(<br>"; $keys = array_keys($avar); foreach($keys as $name) { $value = &$avar[$name]; do_dump($value, "['$name']", $indent.$do_dump_indent, $reference); } echo "$indent)<br>"; } elseif(is_object($avar)) { echo "$indent$var_name <span style='color:#a2a2a2'>$type</span><br>$indent(<br>"; foreach($avar as $name=>$value) do_dump($value, "$name", $indent.$do_dump_indent, $reference); echo "$indent)<br>"; } elseif(is_int($avar)) echo "$indent$var_name = <span style='color:#a2a2a2'>$type(".strlen($avar).")</span> $type_color$avar</span><br>"; elseif(is_string($avar)) echo "$indent$var_name = <span style='color:#a2a2a2'>$type(".strlen($avar).")</span> $type_color\"$avar\"</span><br>"; elseif(is_float($avar)) echo "$indent$var_name = <span style='color:#a2a2a2'>$type(".strlen($avar).")</span> $type_color$avar</span><br>"; elseif(is_bool($avar)) echo "$indent$var_name = <span style='color:#a2a2a2'>$type(".strlen($avar).")</span> $type_color".($avar == 1 ? "TRUE":"FALSE")."</span><br>"; elseif(is_null($avar)) echo "$indent$var_name = <span style='color:#a2a2a2'>$type(".strlen($avar).")</span> {$type_color}NULL</span><br>"; else echo "$indent$var_name = <span style='color:#a2a2a2'>$type(".strlen($avar).")</span> $avar<br>"; $var = $var[$keyvar]; }}?>I wrote this dandy little function for using var_dump() on HTML documents so I don't have to view the source.<?phpfunction htmldump($variable, $height="9em") {echo "<pre style=\"border: 1px solid #000; height: {$height}; overflow: auto; margin: 0.5em;\">";var_dump($variable);echo "</pre>\n";}?>You can pass arguments like this:<?php$sql = mysql_query("SELECT id, name, value FROM table WHERE cond = 'value'");$s = mysql_fetch_assoc($sql);// Dump variable containing the result of the MySQL queryvar_dump($s);?>The second parameter lets you specify the height of the box. Default is 9em, but if you're expecting a huge output you'll probably want a higher value.<?phpvar_dump($s, "17em");?>Happy var_dumping.You can also use the PEAR package available at http://pear.php.net/package/Var_Dumpwhich parses the variable content in a very pleasant manner, a lot more easier to "follow" than the built-in var_dump() function. Of course there are many others, but I prefer this one, because it's simply to use.Just add at the begining of your file:<?phprequire('Var_Dump.php'); // make sure the pear package path is set in php.iniVar_Dump::displayInit(array('display_mode' => 'HTML4_Text'), array('mode' => 'normal','offset' => 4));?>then, instead of simply using var_dump($foo), use:<?phpVar_Dump::display($foo);?>Read the documentation if you're looking for different output layouts.Cheers!Vladimir GhetauIt's important to note that the output depends on the precision directive.<?phpvar_dump(10000000000000.5); // float(10000000000000)ini_set('precision',-1);var_dump(10000000000000.5); // float(10000000000000.5)?>